Two-shoe industrial type brake



June 1953 A. w. BEDFQRD, JR., ETAL 2,642,160

TWO-SHOE INDUSTRIAL TYPE BRAKE Filed Oct. 1.194s

Fig.3.- I

lnvehtors: Alexander W BedFord Jn Ernest F. Goebz,

b y Their Attorney.

Patented June 16, 1953 UNITED smrg oFF C Application Qctolier 1,1948, Serial No. 52,372

It is a iurther object of our invention to provide a new and improved brake shoe provided with a readily replaceable brake shoe lining.

It is a still further object of our invention to provide a new and improved adjustabl brake shoe mounting particularly applicable to armature actuated electromagnetic brakes.

our invention itself will be more fully undert d dits ari u Qbi and ad an a e urher p e iat d b ef rrin .n o. h ll i etailed s ec icat tak n c n nc n with the accompanying drawing, in which Fig. l is a side elevational view, partly in section, of an electromagnetic brake embodying our invention; Fig. 2 is a plan view, partly in section, of the electromagnetic brake shown at Fig. 1; and Fig. 3 is a detailedcross sectional view taken along the line 3--3 of Fig. 1 to illustrate the brake shoe structure and the spring tension control mechanism for the brake.

Referring now to the drawing, the brake, there shown by way of illustration, comprises abase I ll having a pair of spaced apart upright side portions Mia and ifib providing therebetween an opening for a rotatable brake drum I I. Mounted in the base it at opposite ends thereof and below the center line of the brake drum H, are a-pair of electromagnets l2 and IS. The electromagnets I2 and I3 are provided respectively with movable armatures it and I5 which are pivoted at E5 and i7, respectively, on opposite sides of the base at points above the center line of the brake drum 9 I. The armatures i l and i5 extend downwardly in substantially parallel spaced relation on opposite sides of the brake drum II. On.

each armature, intermediate its ends, there is mounted an arcuate brake shoe including a casting or base member i3 and a removable brake liner ii}. The brake shoes and theirniountings are identical in structure, so that only a single shoe ll be desc ibe in deta Referring by way oi example to the armature I l, the brake shoe base l3 mounted thereon is loosely mounted by means of a ball and socket joint formed at the projecting end of a pin 29 which is adiustably mounted in the armature I4 intermediate its ends. The pin 2i! is transversely 4 Claims. I (Cl. 188,-17 1) disposed in the armature and arranged forrectilinear adjusting movement to compensatev for wear on the brake shoe liner. I9. In the. illustrated embodiment of the invention, the pin 20 is threaded into the armature and provided with an unthreaded projecting end 20a of reduced cross section. The projecting end surface 201 of the pin 25 is of spherical configuration. The pin to has fixedly mounted on the end and thereof, a collar 2i, the external configuration of which is spherical and concentric with the spherical sur face 25b at the end of the pin. The collar 2i andthe end 213a of the pin constitute a spherical bearing member upon which the brake shoe I8 is mounted. For this purpose, the brake shoe casting If; is provided intermediate its ends with a spherical socket formed in arecess in the casting and comprising a sleeve 22 having a spherical inner surface and a socket member 23 having a spherical inner surface concentric with the spherical surface of the s1eeve2 2. In assembled position, the spherical collar 2! nts into the ment of the brake I e S h i a slew/8.22. nd t e s h ca ndsu' iec sec of the pin it bears against the spherical seat in e k t mem 23 The cke memb 23 and the end surface 2th; of the pin 20 constitute a thrust bearing through which pressure is applied to force the brake shoe against the. brake drum ii. In order to keep the ball and socket joint between the armature and the brake shoe. free of dust, dirt, oil, and the like, a flexible bel-r lows 2% is connected at one end to the armature and at the other end to the brake shoe thereby to cover the ball andsocket joint at the end of the pin 2! It will be evident from the foregoing descrip tion of the brake shoe mounting that this mount;

lng may be advanced or retracted in each arma: ture to advance or retract the associated brake shoe toward or away from the drum II. The shoe castings is may thus be readjusted in position as the liners I9 wear to maintain within desired limits the air gaps between the magnets I2 and I3 and their respective armatures I4 and 15.. Moreover, the spherical shoe mounting joints permit an appreciable tolerance in positioning of the brake It with respect to the drum II. For example, the brake axis transverse of the drum I I need not be exactly perpendicular to the drum shaft, and a certain degree of angular misalignel about this transverse axis is permissible.

As shown at Fig. 3 each brake shoe. is movable within a passageway in the base ill, and is provided at its lower end with a pair of spring.-

pressed friction pins I8a to ensure proper retractive movement of the shoe. The pins I80. are loosely and slidably mounted in opposite sides of each brake shoe and are biased apart by a compression spring IBb to engage opposite walls of the passageway in the base I3. Thus, upon retraction, each brake shoe first moves away from the drum along its entire surface within the limit of tolerance provided :by the loose mounting of the pins IBa, and thereafter the lower end of each shoe drags on the pins I361 to ensure proper freeing of the top ends of the shoes.

Each brake shoe casting I8 carries a removable brake liner I9 fixed to a rigid backing plate Isa. The backing plate Illa is preferably metal, and is fixedly attached, as by cementing, to the lining material I9 itself. As shown at Fig. 3, the backing plate I9a is preferably slightly narrower than the lining material I9. The inner arcuate surface, or liner mounting surface, of the brake shoe casting I8 is provided for its entire length with. a wide groove into which the liner backing I9a fits to prevent lateral displacement of the lining. To prevent arcuate displacement of the brake liner I9, I9a, the liner is held between a pair of clamping plates 23 and 21 bolted to the brake shoe casting I8 at opposite arcuately displaced ends of the shoe. Thus, to insert a liner, the top clamping plate 21 is removed and the liner I9, IBa, is slipped out of the brake shoe casting I8 by arcuate movement around the brake drum II. A new liner is then slid in place around the drum with the liner backing I90. disposed in the groove in the brake shoe casting. The liner is slid into the shoe base I3 until it engages the clamp 25 as a stop, and the clamp 21 is then replaced. This replacement operation is permitted by the fact that the top of the brake drum is open and freely accessible.

Between the lower ends of the armatures I4 and I5, and beneath the brake drum I I, there is disposed a tension spring 28 which draws the ends of the armatures toward each other and thus applies the brake by forcing the brake shoes into engagement with the drum II.

The spring 28 is connected at one end to a helically grooved spring seat 29 which is bolted to the lower end of the armature I4. The opposite end of the spring 28 is fastened to a helically grooved traveling nut 30 which is mounted on a rotatable threaded shaft 3 I. The threaded shaft 3| is rotatably mounted upon the lower end of the armature i5, and provides for adjustment of the tension exerted by the spring 23 upon the armatures l4 and I5. As shown at Fig. 3, the shaft 3I carries a spur gear 32 which meshes with a worm 3-3 fixed. to a transverse shaft 34. The end of the shaft 34 projects through an aperture in the side of the casing Ill to facilitate spring adjustment. Adjustment of the spring tension is accomplished by turning the shaft 34 and thus rotating the shaft 3 I, thereby to move the traveling nut 33 along the shaft 3|.

The traveling nut 30 is provided with a laterally extending pointer 33a, the end of which extends through an elongated aperture 30?) in the side of the base It to indicate the magnitude of the spring tension, or equivalent brake torque.

The lower ends of the armatures I4 and I are provided, respectively, with laterally extending pointers 35 and 36, the ends of which project through apertures in the side of the base II! to indicate the magnitude of the gap between each armature and its cooperating magnet pole face. It will be understood that if because of wear on a brake shoe lining, the armature gap becomes brake shoe mounting pins 25.

larger than desirable, adjustment may be made at the adjustable brake shoe mounting pin 2!! to return the armature gap to the desired length with the brake shoe engaging the drum.

Means are provided for manually releasing the brake by mechanically forcing apart the arrna-- tures I4 and I5. This mechanical release com prises a pair of oppositely extending rods 31 and 38, the proximate ends of which engage a cam 39 and the remote ends of which are arranged to engage the armatures I4 and I5, respectively. The cam 39 is connected by a rotatable shaft 49 to an operating arm 4I on the outside of the base I 0. The rods 31 and 38 are held against opposite sides of the cam 39 by a tension spring 42 connected between the rods.

It will now be observed that, in operation, the spring 28 normally draws the armatures I4 and I5 toward each other and thus applies the brake by pressing the brake shoes I8, I8 against the drum II. The pressure exerted by the brake shoes is dependent upon the tension of the spring 28 and this, in turn, is controlled by the position of the traveling nut 33. In this applied position of the brakes, the air gaps between the armatures I4 and I5 and their associated magnet pole faces are independently controlled by the adjustable These gaps should be set between the desired maximum and minimum values, and should be reset as the brake linings wear to compensate for such wear. The magnitude of the air gaps is indicated by the pointers 35 and 36. When it is desired to release the brakes, the electromagnets I2 and I3 are energized to attract their respective armatures I and I5, thereby to draw the brake shoes away from the brake drum II. Manual release of the brake is accomplished by turning the handle 4| in either direction, thereby mechanically to force the armatures I4 and I5 into engagement with the magnet pole faces by means of the rods 3"! and 38.

It will be further observed that, because of the arrangement of the energizing magnets I2 and I3 on opposite sides of the brake drum below the center line of the drum, and the position of the biasing spring 28 between the armatures beneath the drum, the brake shoes I8, I58 and the brake drum I I are readily accessible from the top and ends of the drum. This arrangement of the operating parts, in combination with our new and novel end clamping arrangement for the brake shoe linings, permits quick and easy replacement of the brake linings by simply sliding new linings arcuately around the drum from the open top of the drum into position in the brake shoes. Because of this provision, it is unnecessary to remove the brake shoe castings I8 bodily from the base I0 in order to replace the linings. Readjustment of each brake shoe upon replacement of a lining is easily and quickly accomplished simply by adjusting the associated brake shoe mounting pin 20, the end of which is readily accessible at the exposed rear of the armature. Our open-top construction also permits ready removal of the brake drum I I by upward movement, without prior removal of the brake shoes I8, I9.

While we have described by way of illustration a preferred embodiment of our invention, many modifications will occur to those skilled in the art and we, therefore, wish to have it understood that we intend in the appended claims to cover all such claims and modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electromagnetic brake comprising a brake drum, a movable armature pivotally mounted for movement toward and away from said drum, a transverse pin adjustably, mounted in said armature, said pin having a projecting end provided with a spherical end surface, a collar fixedly mounted on said projecting end and providing a spherical outer surface concentric with said spherical end surface, an arcuate brake shoe provided intermediate its ends with a spherical bearing socket mounted upon said collar, said socket including a spherical portion, bearing directly against said spherical end of said pin, means for biasing said armature to bring said shoe into engagement with said drum, and an electromagnet for moving said armature to a predetermined fixed position of retraction to release said brake.

2. An electromagnetic brake comprising a brake drum, a movable armature pivotally mounted for movement toward and away from said drum, electromagnetic means for attracting said armature to a predetermined fixed retracted position, a bearing pin provided with a projecting end and adjustably mounted in said armature for rectilinear movement transverse of said armature, and an arcuate brake shoe having intermediate its ends a ball and socket connection with the projecting end of said pin.

3. An electromagnetic brake comprising a brake drum, a movable armature pivotally mounted for movement toward and away from said drum, a bearing pin adjustably mounted in said armature for rectilinear movement transverse of said armature, said pin having a projecting end providing a spherical bearing member, said bearing member including a spherical end surface of said pin, an arcuate brake shoe provided intermediate its ends with a spherical socket .in which said bearing member is positioned, said end surface of said pin bearing directly against a portion of said socket, means for biasing said armature to bring said shoe into engagement with said drum, and an electromagnet for moving said armature to a predetermined fixed position of retraction to release said brake.

4. An electromagnetic brake comprising a rotatable brake drum having a horizontal shaft, a base member provided with a. pair of stationary upright supporting members on opposite sides of said drum extending from the general horizontal plane of said base a distance substantially equal to the distance between said plane and the point on the periphery of said drum most remote from said plane, a pair of magnetizable armatures disposed on opposite sides of said drum, pivotal connections between said armatures and said upright members at the free ends of said upright members most remote from said general plane of said base member, said armatures extending toward said base in substantially parallel spaced relationship, a pair of arcuate brak shoes, each pivotally mounted on a corresponding one of said armatures intermediate its ends in position to engage said drum, spring means disposed between said drum and said genera"; horizontal plane of said base and attached to said armatures for biasing said armatures to press said shoes into engagement with said drum, and a pair of electromagnets disposed on the side of the center line of said drum nearest said general plane of said base and each mounted on said base in attractive relation to a corresponding one of said armatures to attract said armatures to brake releasing position.

ALEXANDER W. BE-DFORD, JR. ERNEST F. GOETZ.

References Cited in the file of this patent UNITED STATES PATENTS 

